Express-News
Saturday, February 14, 2004
By Calvin Finch, Conservation Director, SAWS, and Horticulturist

TOP DRESSING AND AERATION

            Are you getting the “itch” to work on your lawn? Looking for an excuse to spend some time in the beautiful weather and maybe get some exercise as well? Whatever you do, do not fertilize! Our warm weather grasses—St. Augustine, zoysia, Bermuda, and buffalo grass—are not ready to use fertilizer. The roots are fully operational and nutrients can be pulled from the soil only after the soil warms up and the top is growing. May 1 is the best time to fertilize.

            What you can do is aerate and top dress the lawn; it is relatively easy, provides fine exercise, and it is a magic elixir for your grass.

            Rent an aerator from your neighborhood rental store. Seek one of the machines that has blades that cut plugs from the sod and lay them out on the surface of the lawn as you guide it over the lawn. The spike type aerators are okay, but it bothers me that they are opening up the soil by compressing the sides of the hole they make.

            Taylor Rental (6960 Bandera Rd, 681-2434), the store in my neighborhood in the Medical Center area, charges $24 plus tax for a two-hour rental or $58 plus tax for an all-day rental.  A deposit of $35 is required. They also deliver and pick up the machine for an extra charge, depending on the distance from the shop. It takes about one hour to aerate the typical lawn. Some neighborhoods share the machine and rental fee for a weekend.

            Aerating clay soil opens up the compacted soil to allow oxygen and water to penetrate to 4 to 6 inches. Roots can only survive in soil where moisture and oxygen are available. A compacted soil produces a stressed lawn that is susceptible to drought and disease. It is good to aerate every two years; every year is better. Use the aerator on soils that are moist but not soggy. The plugs should fall easily from the blades. When you are finished the lawn should look like it is covered with cigar butts. Do not worry, they will disintegrate and disappear within a few weeks.

            Aeration is important to a healthy lawn. It can have even more impact if the lawn is top dressed right before or after the aeration. Top dressing involves spreading compost one-half inch deep over the lawn. The compost infiltrates into the aeration channels to replenish organic material in the root zone with the result that the soil does a better job of holding moisture and nutrients for use by the grass. Compost is naturally full of air channels, so it does not block the air and moisture from traveling into the soil through the aeration cuts even if it fills them.

            Take the time before you aerate to mark sprinkler heads with flags so they do not get run over! It is no fun to have broken heads the first time you turn your sprinkler on next summer.

            Some top dressing mixes include sand. They are fine if you are trying to level the lawn but the sand is filler. Pure compost is the same price or may even be less expensive than sand- diluted top dressing, so why buy the filler? Purchase 1 cubic yard of compost for every 640 sq. ft. of lawn to top dress. It is priced at about $20--$30/cu. yd. Delivery is another $35 per truckload (1 to 5 cu. yds. per truckload).

            Spreading compost is easy work. You do not have to be precise or fast but, if you would prefer to have someone else do it, check out Oak Hills Top Soil in Boerne (1-830-249-3575). They offer a unique service where they blow the compost evenly over your lawn with a big reverse vacuum cleaner trailer. For about $55--$60 per cubic yard they will be in and complete the work in minutes. They also offer aeration services.

            Whether you guide the aerator and spread the compost yourself or hire someone to do it for you, it will do wonders for your lawn.